Orcas are the first non-human animals shown to evolve based on culture

Different orca cultures have clear genetic differences.

Orcas are one of only a few animals known to pass down culture.
(Photo: Robert Pittman/NOAA)

Orcas are among the most intelligent creatures on the planet, as well as one of the few non-human creatures known to possess and pass down culture. Now researchers also believe that the culture of these majestic animals has shaped their biological evolution, which would put them in an exclusive club with only humans, reports New Scientist.

Although we now recognize culture in a number of creatures besides ourselves, including primates, cetaceans and some birds, scientists have still held human culture in particular esteem due to its ability to drive biological evolution. For instance, the regional cultural practice of consuming dairy products caused some distinct human populations to become lactose tolerant. This sort of cultural/genetic co-evolution has only been recognized in hominins like us ... that is, until now.

New analysis of the genetics of five distinct orca cultures, performed by Andrew Foote at the University of Bern, Switzerland, and colleagues, clearly shows similar patterns as seen in human populations when it comes to the co-evolution of genomes and culture.

Foote's team looked at the genomes of two killer whale cultures in the Pacific Ocean and three cultures in the Antarctic Ocean. The genomes were shown to clearly fall into five different groups, which just happened to coincide perfectly with the cultural distinctions.

“This is an extremely important piece of research,” said Hal Whitehead at Dalhousie University in Halifax, Canada. “The results are fascinating. We now see how in killer whales, as in humans, culture is not only an important factor in the lives of the whales, but also [helps drive] genetic evolution.”

One category of behavior that is known to set different groups of orcas apart is hunting behavior. Different groups will not only hunt different sorts of prey, but they will display unique hunting techniques and strategies that are learned behaviors not seen in other populations. For instance, some orcas prefer to hunt fish, and they have developed elaborate fish-herding techniques. Other groups hunt seals, and have learned to beach themselves to pursue seals attempting to escape on land. Distinct orca vocalizations have also been recognized, indicating that there are language barriers between different groups too.

It's not easy for these distinct groups to mingle; they hunt different prey, have different techniques, and even have different languages. So they also rarely breed, which eventually leads to distinct genomes.

The complexity of killer whale intelligence and culture is certainly something to consider when thinking about placing these animals in captivity. Not only can captivity mentally damage orcas, but because of the importance of their cultures it also makes them problematic to reintroduce into the wild. For instance, Keiko, the killer whale that was featured in the movie "Free Willy," was released into the wild but was never accepted by any wild pods.